| Project/Area Number |
13305004
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
表面界面物性
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HASEGAWA Shuji The University of Tokyo, Department of Physics, Associate Professor (00228446)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUDA Iwao The University of Tokyo, Department of Physics, Research Associate (00343103)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥39,130,000 (Direct Cost: ¥30,100,000、Indirect Cost: ¥9,030,000)
Fiscal Year 2002: ¥10,140,000 (Direct Cost: ¥7,800,000、Indirect Cost: ¥2,340,000)
Fiscal Year 2001: ¥28,990,000 (Direct Cost: ¥22,300,000、Indirect Cost: ¥6,690,000)
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| Keywords | Four-point probe / Metal-insulator transition / Peierls transition / Surface electrical conduction / Silicon / Surface superstructure / Weak localization / Quasi-one-dimensional metal / 2次元吸着原子ガス / 4探針 / 超高真空 / 光学顕微鏡 / RHEED |
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| Research Abstract |
We have developed a ultrahigh-vacuum system for electrical conductivity measurements with high surface sensitivity by using monolithic micro-four-point probe method (probe spacing being 4〜40μm) at temperatures ranging from 10 K to room temperature, combined with simultaneous structure analysis by reflection-high-energy electron diffraction (RHEED). This apparatus enables direct measurements of electrical conductivity at the topmost atomic layers on crystal surfaces as a function of temperature. We have made several new findings with this apparatus.
(1)A quasi-one-dimensional metallic surface, Si(111)-4×1-In, was found to show a metal-insulator transition around 120 K as revealed by a dramatic increase in resistance by cooling. This is consistent with a picture of Peierls transition accompanied with charge-density waves.
(2)A two-dimensional metallic surface, Si(111)-√3×√3-Ag, was found to show a metal-insulator transition around 230 K as revealed by a dramatic increase in resistance by cooling. Combined with photoemission spectroscopy study, the low-temperature phase is not a band insulator. Weak localization may play a role.
(3)A quasi-one-dimensional metallic surface, Si(557)-Au, was found to be semiconductive in terms of electrical conduction. This may be due to atomic defects which break up the metallic atomic chains into segments.
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